Asian common toads (Duttaphrynus melanostictus) have begun to invade Madagascar, threatening the biodiversity of its unique fauna. Time is short, so we are issuing an urgent call to the conservation community and to governments to prevent an ecological disaster.
The first reported sighting of D. melanostictus on Madagascar was on 26 March in Toamasina. We collected six adult toads from a swamp in the humid eastern region, six kilometres from Madagascar's largest seaport. More were spotted nearby, suggesting that they arrived from Asia inside shipping containers, as they have elsewhere (see F. Kraus Alien Reptiles and Amphibians; Springer, 2009).
The region provides ideal resources and climate for the toad's spread into the island's interior, and D. melanostictus can range up to an elevation of 1,800 metres. Surveys are now being directed by the biodiversity organization Madagasikara Voakajy to identify the extent of invasion and develop a programme of eradication.
The species poses a significant risk to native fauna, given its life-history characteristics, the evolutionary naivety of the native fauna to toad toxins, and the damage caused in Australia and elsewhere by its relative, the cane toad (Rhinella marina).
Without swift eradication of D. melanostictus, the ecological consequences of an invasion include poisoning and decline of vulnerable native predators (birds, mammals, reptiles), the spread of amphibian diseases, and the secondary effects of food-web disruption. Potential impacts on humans include loss of domestic animals, contamination of drinking water and transmission of parasites in areas with poor sanitation.